Modern large-scale coal gasification technology is applied in chemical synthesis raw gas production, synthetic natural gas production and integrated gasification combined cycle (IGCC) power generation. However people are forced to ignore potential or existing environmental pollution caused by this process as reducing power output would be in conflict with the pursuit of economic development. Nearly all effluent discharged by coal gasification processes is harmful to the environment to different degrees. If proper water treatment on the effluent is not carried out, the impact on the environment is immediate and also long term. The purpose of economic development is to improve living conditions, yet damage to the environment will directly or indirectly destroy our living, but the sufferer of environmental destruction is not always the beneficiary of economic development. Due to the abundance of water, normally the beneficiary of economic development is not the sufferer of the waste effluent. This might be the one of important reasons that why economic development cannot harmonious coexistence with environment. Based on the harmonious requirements of national, local economic development and improvement of people's livelihood, the current ineffective coal gasification waste effluent control needs to be improved. The severe environmental pollution problems caused by coal gasification effluent needs to be solved.
Currently, treatment on effluent discharged by coal gasification is basically passive, for example the water treatment will be only carried out after the waste water been generated and discharged from the main production process. As the waste effluent has already been formed and discharged, any after treatment process is ineffective to remove pollutants. At the same time, there will be a certain parts of the waste effluent that could be recyclable resourced, therefore direct discharge of the waste water is a waste of resources.
Accordingly, there is a need for an improved method for waste water purification in the coal gasification process.